1. Field of the Invention
The present invention relates to a method and apparatus for detecting a repetitive pattern in an image.
2. Description of the Related Art
To detect a defect in a semiconductor wafer or an organic light-emitting diode (OLED), light-emitting diode (LED) or liquid crystal display (LCD) substrate, a technique (such as automatic defect classification) of detecting a defect by sensing an appearance defect is being used. This visual detection technique can save production cost by detecting a defect relatively quickly and significantly reducing a defect rate.
The conventional visual detection technique detects a defect in a test image by comparing a reference image of a wafer or substrate without a defect with the test image. Therefore, the conventional visual detection technique essentially needs a reference image of a wafer or substrate without a defect.
However, in some cases, it may be difficult to provide a reference image. For example, it may be technically difficult to satisfy requirements for resolution and precision, or there may be constraints of production cost and time needed to form a reference image for each unit process.
In such cases, it is required to detect a defect in a test image without a reference image.